Postretirement Plans (Net Periodic Benefit Cost Tables) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 1	$ 2	$ 2
Interest cost	498	613	1,493	1,841
Expected return on plan assets	(963)	(938)	(2,894)	(2,816)
Amortization of prior service credits	(20)	(20)	(60)	(60)
Recognized net actuarial loss	304	258	924	774
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	152	3	156	6
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(29)	(83)	(379)	(253)
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	22	22	66	65
Interest cost	23	35	68	107
Expected return on plan assets	(3)	(1)	(6)	(6)
Amortization of prior service credits	(9)	(12)	(26)	(29)
Recognized net actuarial loss	(17)	(10)	(52)	(33)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment		(2)		(2)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	16	$ 32	50	$ 102
BA_Company_Pension_Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	151
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax	1,642
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		2.80%		2.80%	2.60%
BA_Company_Pension_Plan | Measurement Input, Discount Rate
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement	923
BA_Company_Pension_Plan | BA_ReturnOnPlanAssets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement	719
Operating Income (Loss) | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes		$ 1	2	$ 2
Operating Income (Loss) | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	22	23	66	67
Other Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	(29)	(84)	(381)	(255)
Other Income | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	(6)	10	(16)	37
Operating Income (Loss) Before Taxes | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	(29)	(83)	(379)	(253)
Operating Income (Loss) Before Taxes | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	$ 16	$ 33	$ 50	$ 104